The 7th International symposium on Negative Ions, Beams and Sources (NIBS'20)

Different characteristics of plasma meniscus formation between positive and negative beam extraction

2 Sep 2020, 05:40

20m

Oral H– and D– sources for fusion, accelerators and other applications H– and D– sources for fusion: Oral session O1

Speaker

Prof. Kenichi Nagaoka (National Institute for Fusion Science/Nagoya University)

Description

Plasma meniscus is widely believed to be formed in negative ion beam extraction boundary as well as positive ion beam extraction boundary, because very similar perveance dependence of beam divergence is generally observed. However, several difference properties of plasma meniscus formation were revealed in recent studies of negative ion beam focusing. In this talk, the different responses between negative and positive ion meniscus to externally applied perturbation [1-2] and unique phase space structure of negative ion beam [3] are reported. It was also found that the electron current does not affect the beam divergence/meniscus formation [4]. Based on these results, new physical picture of meniscus formation of negative ion beam extraction will be discussed.

This study was supported by JSPS KAKENHI Grant number 17H03002, 17K14903, 19H01883 and 18KK0080, and NIFS (NIFS18ULRR702, NIFS19ULRR031, NIFS20KLER103).

[1] K. Takahashi, T. Imagi, et al., New Journal of Physics 21, 093043, 2019.
[2] Y. Haba, K. Nagaoka, et al., Japanese Journal of Applied Physics 59, SHHA01, 2020.
[3] Y. Haba, K. Nagaoka, K. Tsumori, et al., New Journal of Physics 22, 023017, 2020.
[4] M. Kisaki, K. Ikeada, Plasma and Fusion Research 13, 1205110, 2018.

Presentation Materials

Nagaoka_NBIS2020_v4.pdf